Oh great and powerful OZ! EI tuning question - The Planted Tank Forum
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post #1 of 23 (permalink) Old 08-07-2012, 12:27 AM Thread Starter
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Oh great and powerful OZ! EI tuning question

New user, first post!
I've been working on a tank for my wife's fishies for awhile - not my first tank but my first high tech planted tank. Overall I am very pleased with how things have been going, but I have some plant nutrition questions for the experts.

The tank is a 29 gallon hex tall tank. It runs 2 AHSupply 24w HO compact fluorescents with reflectors on a 10 hour cycle. CO2 is run on a PH meter. Filtration is a large external canister with UV, filter pads and Kaldnes K2 media. I have been dry dosing EI for a few months now and have good growth and healthy fish. As you can see from the pictures, however, there are a few problems that I'd like your experience managing.

Things that I am seeing:
1) The swords leaves are a bit twisty and some leaves come up crumpled. I expect this is a deficiency of something...

2) Some leaves grow and dissolve. Another deficiency.

3) Overall the algae remains <just> under control. No big breakouts or anything with this tank so far (yay!), but there's a constant low level of the 'stubble' growth on leaves in high light, and the growth of the 'spots' in low light areas. Often also on the leaves that are dissolving.

Now on with the pictures!
(these pics make it look MUCH worse than it is - I wanted to capture the problem. This is as bad as it has ever been and usually is much less prominent but that's why I'm here!)







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post #2 of 23 (permalink) Old 08-07-2012, 01:34 AM
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Hi, and welcome to the forum! How long has the tank been up and running?

I know you said you've been dosing EI ferts, but can you detail what you've been dosing, how much, and when?

Do you have a drop checker for the CO2? If so, what color is it reading? If not, try to describe how much CO2 you're injecting. Are you injecting it 24/7 or do you turn it off? If it's turned off, when do you turn it on/off in relation to the lights?

What are your readings for ammonia, nitrite, and nitrate?

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post #3 of 23 (permalink) Old 08-07-2012, 01:37 AM
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The algae in the pictures looks like it could be Oedogonium. Look at it on this page to see if it looks similar: http://www.theplantedtank.co.uk/algae.htm. There are a few more pictures in google images: http://www.google.com/search?num=10&...w=1680&bih=914

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post #4 of 23 (permalink) Old 08-07-2012, 03:21 AM Thread Starter
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Thank you very much for your response!

The tank has been up and running for about 8 months now. I just finished the third culling and replanting this past weekend which involved removing the fish and cleaning into the substrate as the heavy low-level planting in sand makes all but a surface cleaning all but impossible. As a result, the current readings of nitrate, nitrite, and ammonia are all 0. The aquarium and filtration is well cycled and at the weekly water changes (50%) remain at 0. I have not recently taken nitrate or nitrite readings but will midweek to see where we are.

I've not been running a drop checker; KH and GH of my water are both relatively high (very high calcium and lime), and natural PH is 7.5-7.6. I have set the CO2 to 7.0, and it generally hovers between 7.1 and 7.0. A dropchecker is on my list, but I haven't had the impetus to pick one up - LFS in the area do not appear to carry them so I have been waiting for another 'need' before I paid more for shipping than for the dropchecker. Lazy, I know. The fish seem to like it around 7.1. At 6.8 they start to start surfacing for a gulp now and again. This led me to my current setting as 'safe' for the fish. No losses for about a year.

I was initially concerned that it might be BBA, but it is never black nor does it clump even if it grows heavily. I ran across another algae that pointed to a potassium deficiency but I don't remember the name off the top of my head. I'll do some research tomorrow to see if I can locate it again. Growth has been exceedingly slow, and it only appears to grow on the lit side of leaves or the tank sides, very rarely where dark or shaded.

I've been dosing dry every other day for ferts and CSM+B on the off days. I dose the trace wet per (Wet's) calculator based on 40 gallons of water (about 4 gallons in the filter, plus tubing as the filter is remotely located, rounded up). I've recently started including a small quantity of potassium sulfate into the mix slowly, but had not seen a reaction in either the plants or the algae. About equal in the mix to KH2PO4 by weight. Instead of just throwing more 'stuff' into the mix and getting into trouble, I thought I'd ask someone before getting to deep.

I'll post more accurate numbers of the mix tomorrow when I have more time, but it's straight from the Daily EI calculations for 40 gallons. I calculated for 500ml fluids, 10ml daily dosing, then divided the resultant weight by 50 and dose that much a day.

Thanks,
Todd

Edit:
Oh, yes. CO2 is run entirely on PH. It is not synchronized to the lights. A very small stream of air is provided to just break surface tension to allow some offgassing which keeps CO2 cycling. About a dozen bubbles a second, give or take.

Last edited by highly; 08-07-2012 at 03:37 AM. Reason: edited for content
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post #5 of 23 (permalink) Old 08-07-2012, 06:42 AM
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Whether that algae is Oedogonium or not I haven't seen it in my tank since I started using CO2. A very rough rule of thumb is to drop the pH of the tank 1 degree and you are only able to do half that right now. I suspect too much light and not enough CO2. Either drop the lighting intensity and increase the CO2 without bothering your fish. How strong is the ripple on the water's surface? Perhaps you can increase that. I think I would prefer more water movement than a slow rate of bubbles from an airline. How strong is your filter? Perhaps more water movement would help? With the deep tank perhaps a power head deep in the tank pointed up would move bottom water up and put a good ripple on the surface.

First I would decrease the light intensity by shortening the period to 8 hours or raising the fixture 4" or so or placing some thing to shade the surface like window screen down. Choose one to try at a time. Then I would look to getting more water movement in the tank to allow nutrients to reach all parts of the tank and get more oxygen in the water. Then I would drop the pH point of the water by .1 every couple days attempting to get pH to at least 1 degree lower than degassed tank water.

Then lets talk NPK+micros. You are already dosing a good amount of stuff, I think the CO2, O2 and water movement might be improved here.


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post #6 of 23 (permalink) Old 08-07-2012, 11:40 AM Thread Starter
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Kathyy-

Thanks for the reply. Yes, clearly something's not quite right here, and I thank you for the recommendations! Before I left this morning I began the CO2 push so we'll see where that gets us.

I've set the tank up with a strong circular current. I believe in very heavily overfiltering the water! The Aquatop CF400UV is rated for a 110g tank and 370GPH. Correcting for it's Chinese heritage and the 15' of 5/8" tubing, even 50% of that flow is a reasonably stong current in a roughly circular tank. Turnover of better than 6 per hour worst case. I have the 'spray bar' set vertically in the tank reaching down to the last few inches near the bottom. It can just be seen in the second picture. This is creating enough movement in the tank that everything sways as if it were in a moderate breeze, constantly in motion. A .5mm bubble leaving the CO2 stone beneath the spray bar makes a circular track around the tank reaching the surface roughly 5/6 of the way around, and any leaves the Plecos knock free spin in a 3" circle centered on the water's surface. The air bubbler is only there to get the surface to break a little bit to allow oxygen exchange - there is very little surface in a hex! The circular flow does not create a surface ripple.

At 24 watts apiece, the lights provide less than 2 WPG in a very deep tank. There is a pane of glass between the lights and the surface and about 3" bulb-to-water, roughly 30" from the surface to the bottom. The glass is there to protect the bulbs from the ghost catfish that like to make Kamikaze runs straight up, break the surface, and plummet back down so I wanted to avoid calcium buildup on the bulbs from the splash. There is generally some buildup on the glass, further reducing output. Lighting has been reduced from a 12 hour photoperiod to 10 as it is. Are you still of the opinion that light should be further restricted?

Overall the proliferation of algae in the tank has been significantly reduced with the strong plant growth after adding CO2 and ferts. I generally trim the tank back roughly 25% every other water change (two weeks) to prevent choking the flow in the tank with biomass. I had been treating about monthly with a bit (~ level teaspoon or so before a water change) of Sodium Percarbonate to control the little bit that grew on the leaves' surface but would like to gain better control of the tank. The 'spot' algae is new to the tank - I'd never seen it before going high tech. The green beard algae is not new, but is VASTLY reduced. Nevertheless it makes slow but steady progress in the tank.

I will look into a powerhead for the tank. A rough guesstimate as to an appropriate size to the situation would be helpful. I await your suggestions on the lighting as it really does not seem like there is a LOT of light at depth currently.

Thanks again!
Todd
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post #7 of 23 (permalink) Old 08-07-2012, 05:17 PM
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Personally, I don't think lighting is the issue. If the algae is indeed Oedogonium, as it appears to be, then the issue is low CO2 and low nutrients. That's why I asked you to detail what you dose, how much you dose, and when you dose it. Every now and then there is a misunderstanding of the EI charts so it's best to go over those details to double check that area.

I am in agreement regarding the CO2. Kathyy is spot on regarding the 1 degree pH drop as a general measure. Since you don't have a drop checker, you can use that as a rough gauge. Since you described seeing actual CO2 bubbles in the tank, it appears you're using a diffuser. Your flow and circulation sound very good, but it does appear you need to increase your CO2. Also, I'm wondering if the CO2 is being pushed on the outer edges of the tank, but not migrating to the middle portion.

Continue increasing the CO2. As you approach a 1 degree drop in the pH, be sure to watch your fish very closely, especially at night. If you see any signs of stress (gasping at the surface), lower the CO2 a notch. You can do a water change to help the fish. That one notch lower setting on the CO2 then becomes your final setting. It is the highest you can safely go.

Meanwhile, get some H2O2 (regular drug store 3% hydrogen peroxide) to kill the algae. Use no more than 1ml per gallon, so in your case, that would be 29ml total. Turn off your filter and use a syringe to squirt the H2O2 directly onto the algae. After you've used up all 29ml, turn off your lights and wait 15 minutes. After 15 minutes, turn on your filter, but leave your lights off. Wait another 15 minutes. Then turn your lights back on. You can do a 50% water change if you want, but it's not necessary (H2O2 breaks down to water (H2O) and oxygen (O) which is harmless). You should see lots of fizzing where the H2O2 hits the algae. By the next day, the algae should show signs of death, and within a week, it should be melted away.

You can repeat the H2O2 treatment every day until you've killed all the algae. And as long as you have corrected the problem that allowed the algae to grow in the first place, then the algae should not return.

So: (1) confirm fert dosage, (2) increase CO2, and (3) kill algae with H2O2. Hope that helps.

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post #8 of 23 (permalink) Old 08-07-2012, 05:49 PM Thread Starter
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I'll get started on the algae management plan and report back my actual dosing of the ferts.

Any general recommendations for the curling/wavy sword leaves or the dissolving on the leaves of the other plants?

Finally, is there a how-to on the proper way to prune plants like swords? It's difficult to get down into this deep aquarium for pruning and I'm interested if there are any preferred ways to make the cut or if it even matters at all.

Thanks again!
-Todd
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post #9 of 23 (permalink) Old 08-07-2012, 07:06 PM
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No surface ripple? Get one! Your tank is deep and doesn't provide good gas exchange compared to a shallow tank. I wouldn't count on the bubbler to do as good a job as the filter's output, try moving the spraybar up a bit. My pumps can move the surface water really well with the top discharge of the spray bar a couple inches below the water's surface they don't need to break the surface of the water to help oxygenate the water. Your fish are miserable once the CO2 gets over .5 degree pH drop because there isn't enough oxygen in the water in the first place and they struggle when when you start introducing CO2.

For swords it is much better to push down to break the leaf off the crown rather than cut the leaf but that isn't easy to do. Is easier to do with fading leaves than nearly perfect leaves as well.


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post #10 of 23 (permalink) Old 08-07-2012, 07:11 PM
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I have heard that twisted growth (which is actually caused by partial stunted growth) is often caused by low CO2 and/or a calcium deficiency. A calcium deficiency can be caused by two things. You either don't have enough calcium in the tank or your have too much magnesium (or, less likely, too much potassium) which is inhibiting the uptake of the calcium. To figure out which it is, you could measure your Ca and Mg. The Ca:Mg ratio should be 4:1.

As far as pruning swords, basically, you just cut off the older leaves (the ones on the outer part of the rosette) at the base. Any stub you leave will usually fall off in a couple of days so you can follow up a few days later to remove the stub. The closer to the base you can cut the leaves, the better, but it's not that big of a deal. If you can't reach all the way down, then do the best you can. Just try to not leave too much or the sword may not purge the stub. If that happen, you can always just cut it again further down. Sometimes you can even break the leaf off at the base.

Got ninja'd by Kathyy because my daughter interrupted me while I was typing my reply!

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post #11 of 23 (permalink) Old 08-07-2012, 07:22 PM Thread Starter
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Quote:
Originally Posted by Kathyy View Post
No surface ripple? Get one! Your tank is deep and doesn't provide good gas exchange compared to a shallow tank. I wouldn't count on the bubbler to do as good a job as the filter's output, try moving the spraybar up a bit.
OK, I have to ask because I don't understand.

If my spray bar is currently effective (let's assume for the moment) at creating an acceptable flow of water at the lower and mid levels of the tank, and the bubbler is helping to provide the opportunity for gas exchange, and upcurrent, and breaking surface tension... what am I gaining by removing the air and buying a powerhead?

Creating surface agitation with the spray bar would mean neglecting circulation at lower levels (there's only so much flow to go around...). This neglect would force the purchase of a powerhead to increase the flow at the bottom, cost more money, and require more electricity to operate. Besides being different than my current setup, can you explain to me why it would be enough of an improvement over the current solution to justify buying another piece of hardware?

In short... what am I solving by using something besides air to agitate the surface? If there's a significant difference in tank management that I am missing I will entertain the idea, but right now I don't quite understand.
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post #12 of 23 (permalink) Old 08-07-2012, 07:30 PM
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Maybe Kathyy has something in mind with which I'm not familiar, but I don't see anything wrong with using a bubbler to agitate the surface. I may have my own personal preferences regarding the mess bubblers make, but that has nothing to do with their ability to do the task at hand. All that is needed for oxygenation is to break the surface tension which the bubbles do quite effectively.

Now if you were to increase your CO2 and started having problems with the fish showing signs of stress before you've reached a drop of 1 degree in pH, then the issue may need to be revisited (there's always a variance in how many bubbles, etc.). But without any signs of problems, I don't see anything needing to be fixed.

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post #13 of 23 (permalink) Old 08-07-2012, 10:23 PM
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That vertical spraybar has to be the best way to circulate water in your tank, very easy to hide and spreads the water movement along the longest dimension of the tank, nice. Is water coming out of all the holes? I ask because Hoppy wrote a while back that the total area of holes in a spraybar should be about 2/3 the area of the pipe for best flow and that looks like a lot of holes. I have no idea if you could find rigid tubing of the right size to make your own spray bar but I have been making my own for ages and ages out of PVC. The 'expensive' clear ones I have now cost all of $9 as I have a plastics shop a couple miles away.
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I used a plastic air driven box filter for years, worked fine. I hadn't a clue as to how the thing worked at the time but the filter floss sure got dirty fast. I ran a lot more than a few bubbles a minute to get the water moving and it was the bubbles moving through a narrow tube that moved the water more than the bubbles floating up through the water column. My concern is if you are just allowing a few bubbles out of the air pump to keep the surface a bit disturbed are you getting the better oxygenated water down to the bottom of the tank? Surface water could be saturated with oxygen but lower water be poor in oxygen. That is my thought for what it is worth, probably not much! Not really sure your tank could get actually get stratified but that is my thinking.


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post #14 of 23 (permalink) Old 08-07-2012, 10:42 PM Thread Starter
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It sounds like you are talking about an airlift powered box filter. Air lift is an exceptionally efficient way of moving water - significantly moreso than a pump if the head is low.

I would definitely consider the option to 1) run the air stone closer to the bottom and 2) move more air (I have the current output throttled back A LOT). My reading suggested that airstones moving a lot of air in a tank with CO2 is an overall questionable practice. The though was that high agitation of the surface would act to release the CO2 that we are going to such great lengths to get into the water column. I considered the hex tank to be a special exception there inasmuch that you have literally a water column. Very little surface area for oxygen exchange. The thing is...we are feeding our plants heavily in the hope that they will grow, and growing plants produce...oxygen. I opted for just enough air to disturb the surface to allow controlled offgassing and some perturbation to break the biofilm at the air:water interface. This seemed logical to me, and was supported by a slow but constant requirement of CO2 to maintain PH. Turning off the air reduces CO2 cycling and a more stable PH - sometimes not requesting CO2 to lower PH for hours. I took this as an indication that things were working as expected. More air perturbs more surface area resulting in more CO2 demand to maintain the PH drop. I would expect there to be a limit to solubility of gas in water, and that limit will probably (I assume) be a balance of the available gasses. The fish seemed to back this up - they appeared more stressed in the tank with the air off and CO2 the primary gas being added. So this is the balance that I struck and the reason that I chose as I did.

I have considered a longer spray bar setup - I am very familiar with plastics - but hadn't yet found a significant enough deficiency. I may very well look more closely at the currents in the tank as CO2 goes up if I see a change in the behavior of the fish indicating an avoidance of the lower strata.
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post #15 of 23 (permalink) Old 08-08-2012, 02:18 AM
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Kathyy has a valid concern; although, I'm not in total agreement with how to go about addressing the concern. As I understand it, the concern is that the oxygenated water will not migrate downward toward the lower portion of the tank. So even if you do have sufficient oxygen exchange at the surface for the volume of water in the tank, the shape of the tank may create an additional issue of getting that oxygen distributed throughout the tank.

The oxygen will migrate downward as a natural part of diffusion (migration from an area of higher concentration to an area of lower concentration). However, because oxygen is lighter than water, it will also want to migrate upward. If we were to set out a glass of oxygenated water, I believe the oxygen would eventually migrate upward, indicating that the pressure to migrate upward is stronger than the pressure of diffusion. Therefore, you'll need to apply pressure to push the oxygen downward to the lower portion of the tank.

I think you can probably do this easily enough by tilting your spray bar so that it sprays at a slightly downward tilt. This changes the circulation from a simple horizontal pattern to one that is slightly downward in its horizontal path. That's actually good not only for the oxygen, but also for the CO2 since you'll want to push it downward to prevent it from rising to the surface and escaping. Anything you can do to keep the CO2 in the water column longer can help. So this would be beneficial for both, oxygenating the water in the lower portion of the tank and increasing the CO2 saturation. It may also help to ensure that CO2 migrates into the middle of the tank since it will "hit" the bottom due to the downward push. It won't be able to move upward on the sides of the tank because of the current caused by the spray bar so the only place it can go is in the middle. Think of it as a sort of tornado effect.

That way you can keep things as they are, but only make a minor adjustment to the position of your spray bar. It will help with the oxygen and CO2 issues. A win-win-win.

As far as the spray bar diameter vs. holes, and with all due respect to Hoppi, consideration must be paid to the amount of pressure exerted on the water in the spray bar. If the pressure is high enough, the force of the water should be strong enough throughout the spray bar even if it's not perfectly even. On my 75g and 90g tanks, I have double length spray bars that travel the full length of the back wall (close to 48" long), and I am certain the total area of the holes exceeds that of the pipe. However, I have strong enough canisters to supply such a strong amount of pressure that the water comes out very strong through each and every hole. In fact, the pressure is so strong, I have problems with it blowing the spray bars off completely so I have to seal the connections to keep the spray bars on. So the amount of pressure plays a big role in how well the water comes out of each of the holes in a spray bar. I would think that if circulation was a problem, it would already be known by now; therefore, I don't think that's an issue here.

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Pelvicachromis taeniatus 'Moliwe' —— • 75g -
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Pelvicachromis pulcher 'Lagos Red'
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• 29g -
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Pelvicachromis pulcher 'unknown' —-- • 29g - Pelvicachromis taeniatus 'Moliwe'
• 5g - RCS colony —————————————————— • 2.5g -
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Retired
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